Hair styling compositions are well known and are commercially available in a variety of forms including mousses, gels, lotions, pumps, or hairsprays. Many of these compositions contain various hairstyling resins to provide temporary hair styling or "setting" benefits.
Hairstyling resins such as silicone-grafted copolymers are particularly useful in hair styling compositions such as hairsprays because these copolymers can provide good style retention benefits to the hair while also providing improved hair feel. In other words, the silicone-grafted copolymers can impart a tactile sense of softness and conditioning to the hair relative to conventional, non-silicone-containing resins without the tacky hair feel traditionally associated with non-silicone hair fixative polymers. The silicone grafted copolymers are typically used as neutralized copolymers because when these copolymers are used at least in partially neutralized form the copolymers provide for a hairspray composition that is easily removable by water and/or by shampooing and that has improved styling performance.
The use of neutralized silicone-grafted copolymers in hairspray compositions is well known, and typically the copolymers are neutralized with an inorganic or organic neutralizing base. Hairspray compositions which contain an inorganic neutralizing base generally comprise at least about 10% by weight of water to help solubilize the silicone-grafted copolymer. Moreover, aqueous hairspray compositions which contain neutralized silicone grafted copolymers can result in a polymeric film on the hair that feels sticky or tacky to the touch. Therefore, it is desirable to use neutralized silicone-grafted hair styling copolymers in compositions containing less than about 10% by weight of water, and preferably in compositions that are substantially anhydrous, in order to obtain the desired product performance.
One method of formulating hairsprays that contain less than about 10% by weight of water and which also contain neutralized silicone-grafted copolymers involves the use of a neutralizing system comprising a combination of an inorganic and organic base. These hairsprays have a clear appearance, deliver effective style retention, impart a hair conditioning effect, have a non-sticky hair feel, are easily brushed out, and at the same time have stable product and viscosity characteristics and remain fully stable under long term and stressed temperature storage. The neutralizing systems incorporated into these hairspray compositions typically comprise the inorganic and organic bases at selected ratios to achieve the desired copolymer neutralization and the corresponding improvement in hairstyle performance and product clarity. It has been found, however, that the use of neutralized silicone-grafted copolymers in anhydrous hairsprays can result in poor spray performance, especially when the hairspray is formulated as an anhydrous aerosol hairspray. These anhydrous aerosol hairsprays tend to weep and foam at the orifice of the hairspray container during application.
It has now been found that select neutralizing systems can be incorporated into anhydrous aerosol hairspray compositions that contain silicone-grafted polymers to improve the spray delivery performance of the composition. It has also been found that the spray delivery performance can be improved when the composition contains a nonhydrocarbon propellant that is substantially free of any hydrocarbon propellant, e.g. less than about 5% of hydrocarbon propellant by weight of the composition. The select neutralizing systems incorporated in these anhydrous aerosol hairsprays comprise a combination of an organic base at a level sufficient to neutralize from about 25% to about 80% of the acid groups on silicone-grafted copolymers, and an inorganic base at a level sufficient to neutralize from about 0.5% to about 20% of the acid groups on silicone-grafted copolymers.
In view of the foregoing, it is therefore an object of the present invention to provide an anhydrous aerosol hairspray composition which does not weep or foam at the aerosol container orifice during application, and which contains silicone-grafted copolymers and a select neutralizing system to neutralize the copolymers, and which also contains less than about 5% by weight of a hydrocarbon propellant. It is also an object of the present invention to provide an anhydrous aerosol hairspray composition which delivers effective style retention, impart a hair conditioning effect, and does not feel unduly sticky or tacky to the touch.